|
|
|
|
| |
|
|
| |
| SCIENTIFIC
CLASSIFICATION |
|
| COMMON
NAME: |
nurse
shark |
| KINGDOM: |
Animalia |
| PHYLUM: |
Chordata |
| CLASS: |
Chondrichthyes |
| ORDER: |
Orectolobiformes |
| FAMILY: |
Ginglymostomatidae |
| GENUS
SPECIES: |
Ginglymostoma cirratum |
|
|
|
| |
|
|
| DESCRIPTION: |
Body is yellow-brown to gray-brown, with or without
small dark spots and obscure dorsal saddle markings.
Mouth is set forward of eyes and is relatively high
up on the head - maintaining a more forward position.
Noticeable barbells are present, along with nasoral
grooves (though there are no perinasal grooves).
Spiracles are minute. Dorsal fins are broad and
rounded, with the first dorsal being considerably
larger than the second. Dorsal fins are set relatively
far back along the ventral surface. The upper lobe
of the caudal fin is considerably longer than the
lower lobe. The caudal fin itself comprises roughly
one quarter of the overall body length. |
| MALE |
External
claspers located on the far underside of the body
- forward of the caudal fin - distinguish males. |
|
| SIZE: |
300 cm (10.0 ft) avg; 430 cm (14.1 ft) max |
|
| WEIGHT: |
110 kg (242.5 lbs) max |
|
| DIET: |
Nurse sharks primarily feed on benthic invertebrates
(i.e. spiny lobsters, shrimps, crabs, sea urchins,
squids, octopuses, marine snails and bivalves) and
benthic fish (i.e. sea catfishes, mullets, puffers
and stingrays). Though algal species are occasionally
found within their stomachs, nurse sharks are not
considered omnivores. Rather, the algal material
is likely consumed as a consequence to the shark's
pursuit of benthic prey.
The
smallish mouth and large bellows-like pharynx
of the nurse shark allow this species to inhale
prey items with tremendous force and speed. This
powerful suction feeding mechanism combined with
the species' nocturnal activity pattern, may allow
the nurse shark to successfully prey upon small,
active diurnal fish species which are at rest
during the overnight hours. (During the day, such
active, mid-water species would be beyond the
predatory capabilities of the nurse shark.)
Nurse
sharks are known to successfully feed on large,
heavy shelled marine snails (i.e. conches) by
flipping the shell over, exposing the vulnerable
apeture. Using their teeth and suction, the shark
then extracts the snail from its shell altogether.
|
|
| GESTATION: |
Nurse sharks exhibit ovoviviparous reproduction
in which yolk sacks primarily sustain the intrauterine
development of the young. Within the waters adjacent
to Florida, birthing typically occurs in late spring
and early summer months. |
| CLUTCH
SIZE |
Litters
are comprised of 21-28 intrauterine eggs or young
(distinction of "eggs" versus "young"
is dependent on the time of sampling within the
intrauterine development process). |
|
| SEXUAL
MATURITY: |
|
| MALE |
Approximately 225 cm |
| FEMALE |
230-240 cm |
|
| LIFE
SPAN: |
Approximately 25 years in zoological facilities
|
|
| RANGE: |
Western Atlantic: shallow waters from Rhode Island
to Brazil, including the Caribbean basin and Gulf
of Mexico
Eastern Atlantic: tropical West Africa to the Cape
Verde Islands
Eastern Pacific: southern Baja California to Peru |
|
| HABITAT: |
The nurse shark is a common large inshore shark
(primarily benthic) inhabiting the continental and
insular shelves throughout tropical and subtropical
waters within its range. They are often observed
at depths of a meter or less within the intertidal
zone, though they are known to range down to depths
of at least 12 meters. This species is often found
along reef sites, within mangrove channels, and
on sand or seagrass flats. |
|
| POPULATION: |
GLOBAL |
While global population figures are unknown, nurse
sharks are common in shallow waters within their
range. |
|
| STATUS: |
IUCN |
Not
listed |
| CITES |
Not listed |
| USFWS |
Not
listed |
|
|
|
| |
|
|
| 1. |
One
of the distinguishing features of nurse sharks are
their barbells - fleshy appendages which hang below
their nostrils and, in part, provide a sense of
touch which assists in the location of prey along
the bottom. |
|
|
| 2. |
Unlike most sharks, which require constant motion
to move water over their gills and maintain a sufficient
internal blood pressure, the nurse shark often remains
motionless along the bottom - actively pumping water
over its gills through the continual opening and
closing of its mouth. |
|
|
| 3. |
Though documented attacks - some of which have resulted
in painful wounds - are associated with this species,
nurse sharks are generally considered a docile shark
species. Virtually every tallied attack has been
provoked. The nurse shark's tendency to lay motionless
on the bottom seems to lull divers into a false
sense of security - occasionally leading to the
poking, prodding, or pulling of a wild nurse shark.
Such human behavior can lead to defensive actions
on the part of the shark…and ending in an additional
"attack" statistic. |
|
|
| 4. |
Nurse
sharks do well in zoological settings. They have
been documented living to twenty-five years of age
within public aquaria. |
|
|
| 5. |
In
learning experiments, nurse sharks have shown themselves
capable of being trained to swim to a handler to
receive food. |
|
|
| 6. |
For
more information about sharks & rays, explore
the sharks
& rays info book. |
|
|
|
| |
|
|
|
The nurse shark is privately and commercially harvested
for its thick, armor-like hide, which is processed
into an exceptionally good leather. They are also
targeted for consumption, whether it be fresh or
salted. Additionally they are harvested for their
liver oil and for use as fishmeal.
Nurse
sharks have proven to be a hardy, adapatable species
- capable of surviving a relatively broad range
of temperatures and dissolved oxygen levels.
In
1993, the U.S. National Marine Fisheries Service
(NMFS) established a management plan designed
to protect 39 shark species found in Atlantic
and Gulf of Mexico waters. The purview of this
plan encompassed the Exclusive Economic Zone (EEZ)
- the area extending from state waters out to
200 miles offshore. This NMFS plan aims at stabilizing
shark populations through the reduction of commercial
and recreational fishing pressures via licensing
and take quotas. The nurse shark is one of the
39 species covered in this plan.
|
|
|
|
| |
|
|
| Allen,
Thomas B., The Shark Almanac. The Lyons Press,
1999. |
| |
|
Compagno, Leonard J.V., FAO Species Catalog,
Vol. 4 Sharks of the World. United Nations Development
Programme, Food and Agriculture Organization of
the United Nations, Rome, 1984. |
| |
|
www.fishbase.org
|
|
|
|
|
|
|
|
|
|
|
